Telephone-exchange system.



C. W. KECKLER.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED NOV. I7. 1911.

1,279,875. I PatentedSept. 24,1918.

//1 vemor: C/rq/ /es l V. ffec/r/en' Affy.

UNITED srnrns rn'rnnr onmon. f

CHARLES W. KECKLER, OF NEWARK, NEVJ JERSEY, ASSIGNOR'TO WESTERN ELECTRICCOMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of letters Patent.

Patented Sept. 24,1918.

Application filed November 17, 1917. Serial No. 202,501. I

To all whom it may concern:

Be it known that I, CHARLES W. KEGKLER, a citizen of the United States,residing at Newark, in the county of Essex and State of New Jersey, haveinvented certain new and useful Improvements in Telephone-EX changeSystems, of which the following is a full, clear, concise, and exactdescription.

This invention relates to telephone exchange systems, and moreparticularly to such systems of the central energy type employingconnecting or link circuits provided with apparatus for automaticallyapplying ringing current to the called-for line upon connection beingmade therewith. An object of this invention is to provide improvedsignaling means for such systems. Another object of this invention is toprovide a system of this character in which ringing current cannot beconnected with a busy telephone line.

In accordance with the various features of this invention, a connectingor link circuit is provided with relay mechanism and an interrupterwhich cooperate, upon connection of the link circuit with an idletelephone line, to connect the source of ringing current thereto, andwhich, when connection is made with a busy telephoneline, cooperate in adifferent manner to prevent-the connection of ringing current thereto.Upon the line becoming idle by the disconnection therefrom of thepreviously connected link circuit, the link circuit apparatus functionsautomatically to connect the source of ringingcurrent' to the line. Byutilizing the present invention there is obtained a system in which awaiting connection may be established with the busy line and in which,when such line becomes idle, ringing is automatically connected theretofor causing the operation of the usual call bell associated therewith.

For a more complete understanding of this invention, reference should behad to the following description considered in connection with theaccompanying drawing illustrating one embodiment thereof.

'In the drawing the apparatus shown within the dotted lines in the upperleft-hand corner is located at a central oflice X, while the otherapparatus shown on the drawing is located at a central oflice Y, atwhich terminates a telephone line B. A telephone line A, similar in allrespects to B, terminates at the central office X and may be connectedin any desired manner with the cord I circuit C. A trunk circuit Dextending between the central ofiices X and Y may serve to connect cordcircuit C with the telephone line B. The telephone lines A and B and thecord circuit C are of the usual type,-while the trunk circuit D embodiesthe features of this invention. It is to be understood that a pluralityof line, cord and trunk circuits like those shown in the drawing may andusually are provided, but for convenience only the one cord circuit, onetrunk circuit and two line circuits are illustrated. This invention canprobably be best under stood from a description of the operation of thesystem illustrated in the drawing, and

it will be so described.

The operator at central oflice ing advised by the initiating subscriberA that connection is desired with the line of subscriber B, maycommunicate over an order wire circuit (not shown)to the operator atcentral office. Y the number of the wanted line, whereupon the operatorat central officc Y assigns a trunk circuit to be usedin establishingthe connection between lines A and B. Assuming that the assigned trunkcircuit is trunk circuit D, the operator at central office X insertsplug 5 in jack 6 of the trunk circuit, thereby lighting callingsupervisory lamp 9. Trunk relay 7 also operates X, upon be over acircuit from battery through the winding of supervisory relay 8, ringcontacts of the plug 5 and thejack 6, both windings of the trunk relay 7and tip con-' tacts of the jack 6 and the plug 5 to ground. Upon theoperation of the trunk relay 7, lamp 10 is lighted over a circuit frombattery through the lamp 10, contact of trunk relay 7 lower normalcontact of relay 12, and resistance coil 13 to ground. The operator atcentral oflice Y, observing the lighted condition of the lamp 10, notesthat the'origi nating operator has connected the cord circuit O to theproper trunk circuit and-may thereupon test the line B to determine theidle or busy condition thereof. Assuming this line to be idle, plug 20of the trunk circuit D is inserted in jack 21 of the line B, whereuponthe relay 12 and cutoff relay 22 are operated over a circuit frombattery through lamp 10, the winding of relay 12,- sleeve contacts ofthe plug 20 and the jack 21, and the winding of cutoff relay 22 toground. Relay 12, in operating, disconnects the resistance coil 13 fromthe circuit of the lamp 10 and causes the operation of relay 23 over acircuit from battery through the winding of relay 23, normal contact ofrelay 24, normal contactof tripping relay 25, lower alternate contact ofrelay 12, contact of trunk relay 7, the winding of relay 12, sleevecontacts of the plug 20 and the jack 21 and the winding of cutofi relay22 to ground. The winding of relay 23 is of low resistance so that, uponbeing included in a shunt circuit about the lamp 10, it causes this lampto be extinguished. Relay 23, in operating. closes a contact in thecircuit including the righthand winding of relay 26, so that when thecircuit is completed at interrupter 27, the relay 26 operates. Theattraction of its armature upon the energization of relay 26 causes theimmediate operation of relay 29 over a circuit from battery throughcontact 30 of relay 12, the winding of relay 29, and the alternatecontact of relay 26 to ground. Relay 29, in operating, immediately locksup through its left-hand contact and prepares at its right-hand contacta circuit for relay 28 which is completed by the subsequentdeenergization of relay 26. This subsequent deiinergization of relay 26takes place when the brush of interrupter27 comes in engagement with theinsulating segment thereof. The circuit through the right hand windingof relay 26 being open when the insulating segment of the interrupter 27comes into ongagement with the brush thereof, relay 26 releases to causethe operation oi relay 28. Relay 28, in operating, connects ringingcurrent to the called-for line B o er a circuit from a source of ringingcurrent. through the winding 01 tripping relay 25, lower alternatecontact of relay 23, lower alternate contact of relay 28, ring contactsof the plug 20 and the jack 21, call bell 36 and condenser 37 of stationB, tip contacts of the jack 21 and the plug 20, middle alternate contactof relay 12, middle alternate contact of relay 23, and upper alternatecontact of relay 28 to ground. Subscriber B, in responding to theoperation of the call bell 36, removes the receiver from the switchhook,thereby causing the operation of the tripping relay 25. Relay 25, inoperating, opens a short circuit about the winding of relay 2 1,permitting the operation thereof. Relay 24c, in operating, completes alocking circuit for itself and in so doing establishes a short circuitfor the winding of relay 23, which immediately releases, disconnectingringing current -from the called line. The winding of relay 24 which isnow substituted for the winding o1 relay 23 in the shunt circuit aboutthe lamp 10 is also of low resistance so that the lamp remainsextinguished. Relay 23., in releasing completes the talking circuit,

whereupon supervisory relay 38 operates.

Supervisory relay 38, in operating, short circuits the left-hand windingof trunk relay 7, thereby reducing the resistance in circuit with thewinding of the supervisory relay 8 and permitting the operation.thereof. Supervisory relay 8 in operating completes a shunt circuit,including resistance coil 39, about the calling supervisory lamp 9,which is thereby extinguished.

At the conclusion of the conversation the subscribers restore thereceivers to the switchhooks. he restoration of the receiver to theswitchhook at station B causes the deenergization of supervisory relay3S, whereupon the left-hand winding of the trun; relay 7 is againincluded in circuit with the winding of the supervisory relay 8.Supervisory relay 8 thereupon releases, permitting calling supervisorylamp 9 to be lighted. The lighting of this calling supervisory lamp 9and the lighting of the answering supervisory lamp (not shown) of thecord circuit C serve as disconnect signals to the operator, who maythereupon withdraw the plug 5 from the jack 6. The trunk relay 7thereupon releases, opening the shunt circuit of the lamp 10, whichlights to furnish a disconnect signal. to the operator at central ofliceY. The operator, upon observing the lighted condition of this lamp, maywithdraw the plug 20 from the jack 21, whereupon all apparatus isrestored to normal condition. 7

Should another trunk circuit, similar to D, or a cord circuit, similarto C, be connected with another "jack of line B at the time the plug oftruck circuit D is inserted in the jack 21, relays 12, 23, 26 and 29operate in the order hereinbefore described. The relay 26 will not.however, be deenerwhen the circuit of the right-hand winding thereof isopened at the interrupter 27, for the reason that the relay 26 remainsoperated due to a circuit from battery furnished throughpreviously-connected cord or trunk circuit, ring contacts of the plugthereof and the engaged jack, ring contacts of the jack 21 and the plug20, lower normal contact of relay 28, and the left-hand winding of relay26 to groun Belay 26 will, therefore, remain energized as long as theother trunk or cord circuit remains connected with the line B, andringing current cannot be connected thereto by way of the trunk circuitD so long as the other connection remains up. This circuit including theleft-hand winding of the relay 26 is completed as soon as the plug 20 isfully inserted in the jack 21 so that an energizing circuitindependentof the right-hand winding is established when the trunkcircuit D is connected with a busy telephone line.

Then the previously-connected cord or trunk circuit is disconnected fromthe line B, the circuit including the left-hand winding of relay 26 isopened, and the circuit,

including the right-hand winding thereof, will be opened whenever theinsulating segment of the relay 27 engages the brush thereof, so thatrelay 26 is then deenergized, causing the operation of relay 28, asbefore described, whereupon ringing current is connected with line B.Upon the response of subscriber B to the operation of the call bell, thetripping relay 25, relay 24, ringing relay 23, supervisory relays 38 and8, function in the manner hereinbefore described.

It will be observed that ringing current cannot be connected to a lineuntil the following cycle of operations have been performed: first, theenergization of relay 26; second, the energization and locking-up ofrelay 29; third, the release of relay 26; and fourth. the energizationof relay 28. "By providing apparatus functioning in this manner, awaiting connection may be established with a called-for line, and whenthe connection rendering the line busy is interrupted by thedisconnection of the cord or trunk circuit from the line, ringingcurrent is automatically projected over the called-for line by way ofthe trunk or link circuit forming what was the waiting connection.

What is claimed is:

1. A telephone exchange system comprising a telephone line, a linkcircuit for connecting therewith, a first and a second relay in the linkcircuit energized upon connection thereof with the telephone line, athird relay operating upon the energization of the second relay, asource of ringing current, and a fourth relay energized upon thesubsequent deenergization of the second relay while the third relay isoperated to connect the source of ringing current to the telephone line.

2. A telephone exchange system comprising a telephone line, a linkcircuit for connecting therewith, a first and a second relay in the linkcircuit energized upon connection thereof with the telephone line, athird relay operating upon the energization of the second relay, asource of ringing current, and a fourth relay energized upon thesubsequent deenergization of the second relay while the third relay isoperated to connect the source of ringing current to the telephone linethrough contacts of the energized first and fourth relays.

3. A telephone exchange system comprising a telephone line, a linkcircuit for connecting therewith, a first and a second relay energizedupon connection thereof with the telephone line, a third relay operatingupon the energization of the second relay, a looking circuit thereforcompleted upon the operation thereof for rendering this relayindependent of the second relay, a fourth relay, an energizing circuittherefor completed by the subsequent denergization of the second relayand including a contact of the third 7 relay, and a source of ringingcurrent connected with the telephone line upon the energization of thefourth relay.

4. A telephone exchange system comprising a telephone line, a linkcircuit for connecting therewith, a first relay energized uponconnection of the link circuit with the telephone line, a second relay,a normally open energizing circuit for the second relay partiallycompleted upon the energization of the first relay, an interrupter. foralternately closing and opening the energizing circuit of the secondrelay, a third relay operating upon the energization of the secondrelay, a source of ringing current, and a fourth relay operating uponthe subsequent deenergization of the second relay while the third relayis operated to connect the source of ringing current to the telephoneline.

5. A telephone exchange system comprising a telephone line, a linkcircuit for connecting therewith, a, first relay energized uponconnection of the link circuit with the telephone line, a second relay,a normally open energizing circuit for-the second relay partiallycompleted upon the energization of the firstrelay, an interrupter foralter-.

nately closing and opening the energizing circuit of the second relay, athird relay. operating upon the energization of the second relay, alocking circuit for the third relay established upon the operationthereof, a source of ringing current, a fourth relay when operatedconnecting the source of ringing current to the line, and an operatingcircuit for the fourth relay including contacts of the second and thirdrelays and completed upon the subsequent deenergization of the secondrelay.

6. A telephone exchange system comprising a telephone line, a linkcircuit for connecting therewith, a first relay energized uponconnectionof the link circuit with the telephone line, a second relay, a normallyopen energizing circuit for the second relay partially completed uponthe energization of the first relay, an interrupter for alternatelyclosingand opening the energizing circuit of the second relay, a thirdrelay operating upon the energization of the second relay, a source ofringing current, and a fourth relay energized upon the subsequentdeenergization of the second relay while the third relay is operated toconnect the source of ringing current with the telephone line throughnormally open contacts of the first and fourth relays.

7 A telephone exchange system comprising a telephone line, a linkcircuit connected therewith, a second link circuit, a relay in thesecond link circuit energized upon connection thereof with the telephoneline and over a circuit including a portion of the first link circuit, asource of ringing current, and

source of ringing current.

8. A telephone exchaiige systein'coinpris ing a telephone line, a linkcircuit connected therewith, a second ll llliilli'tlllt, afirstre lay inthe second link cii'cuit energi'zed upon connection thereof \Ylili thetelep'l'ione 'hne,

a second relay in the second link circuitenergized'uponconnectionthereof with the --prising a telephone line,link circuits for telephone line and orer'a circuit including a portionor the first link circuit, a third relay operatiiig upon theenergiz'ation of the second'relay; a fourth relay; an energizing circuittherefor including an engaged con-' tact of the ope 'ated th rd relayand coin pleted'uponthe'deen'ergization of the 'second relay when'thefirst link'circuit is disconnected "from the line,and a source ofringing current connected with the tele-' phone line through normallyopen contacts of the first and fourth relays upon'the energization ofthe fourth relay.

9. A telephone exchange-system compris ing a telephone line, a linkcircuit connected therewith, a secoi'i'd'link circuit, a first-relay inthe second link circuit energized upon connection thereof with thetelephone line and over a circuit inclu'din'ga portion of the firstlink'circuit, a second relay operating upon the eiiergization of thefirstu'elay, 'a third relay, an energizing'circuit therefor includingunengaged contact of the operated second relay I and completed by the.deenergization of the first relay when the first link circuit isdisconnected from the tele phone "linejand a source of ringii-i'gcurrent connected with the telephone line by the energiz'ation ofthethirdrelay.

10. A telephone exchange system coinprising a telephone line, linkcircuits for connectingtherewith, a relay in each link Dopie'a'ufthispeteiifmay'b'e'bttahid'fbnfive meteor, by addre ssiri'g theCommissioner of P atehts,

determined period if no other link circuit is connected therewith and itanother link circuit is connected therewith then within thepredeterminedperiod after the disconnection of the other link circuittherefrom,

'a source of ringing current, and a second relay responsive to thedeenergization of the first relay to connect the source of ring ingcurrent to the telephone line.

11. A telephone exchange system coinconnecting therewith, a relay ineach link circuit energized upon connection with the telephone line anddeenergized within a pre determinedperiod it no other link circuit isconnected therewith and if another link circuit is connected therewiththen within the predetermined period after the disconnection "of theother liiikciiciiit therefrom, and a source of ringing current connectedwith the telephone line upon the detinergization of therelay. I

12. A telephone exchange system comprising a'tele'phoneline', linkcircuits for connect- -'ing therewith, a relay in each link'circuitenei'gized upon connection with the telephone line and deenergizedwithin. a predetermined.

period if no other link circuit is connected therewith and it anotherlink circuit is connected therewith then within the predetermined periodafter the disconnection of the other link circuit therefrom, a secondrelay energized and locked up upon the en ei'gization or the firstrelay, a source of ringing current, a third relay, and an energizingcircuit therefor including a contact Washington, D. C.

